placed on, do people just go out and have one particular product that they put on and expect it to come off, or is there some training that's going on to find out, okay, this is the application we need to use for this surface and this is the, you know, a different application we need to use for another surface? and how can you prevent that ghosting? because if it's still there, it's there. just because you remove the pigment doesn't mean that it's gone. and like you stated yourself, when do you say, enough is enough? because if you have an historic building and you want the graffiti removed but you have the ghost there, is it really removed? >> well, historic buildings, dpw would not be removing the graffiti. and remember also on private property, the property owner is responsible for it. dpw as a rule does not do the abatement. so, whether they are or aren't using the correct materials to remove it off of brick, it's based on who they hire or who they get to do the work.